The present invention generally relates to an original document feeding arrangement and more particularly, to an original document feeder provided, for example, in an electrostatic copying apparatus and the like for successively supplying original documents in sheet-form to a reading region.
Conventionally, in an optical reading apparatus arranged to read the surface of an original document through a slit exposure, for example, as in a transfer type electrostatic copying apparatus or the like, there is provided a first type exposing means arranged to effect exposure for reading by moving the optical system, with the original document fixed, or a second type exposing means adapted to effect exposure for reading by displacing the original document, with the optical system held stationary. In the second type exposing means as referred to above, there are cases where a recirculating document handler (referred to as RDH hereinafter) is employed for effecting an automatic transport of an original document in such a manner as to successively feed sheet-formed original documents to a reading region one sheet by one sheet, and to return the original document back to the original position after exposure and reading thereof.
FIG. 5 is a schematic side sectional view of one example for a conventional recirculating document handler RDH1, which generally includes an original document accommodating section 3 for accommodating therein a stack of original documents 2 in a sheet-form to be copied, a support cylinder 5 of a right circular cross section for supporting the original document 2 thereon so as to be passed through a reading region 4, and an original document transport path 8 constituted by a transport passage 6 for transporting the original document from accommodating section 3 to the reading region 4 and another transport passage 7 for returning the original document from the reading region 4 back to the accommodating section 3.
The original documents 2 stacked in the accommodating section 3 for copying are positively fed by sheet feeding roller 9, one sheet by one sheet, from the uppermost portion of the stack into the transport passage 6. The original document transported through the passage 6 is supported by the support cylinder 5 and passed above a transparent plate 10 made of a hard glass material or the like provided at the reading region 4. Onto the surface of the original document 2 passing above the transparent plate 10, light from an exposure lamp of an optical system (not shown) is projected so as to read the image of the original document 2 for effecting copying operation within a housing of a copying apparatus (not shown here). The original document 2 thus read for its one surface is transported through the passage 7, and is accommodated at the lowermost portion of the stack of the original documents 2 stored in the accommodating section 3.
Each time the original document 2 is fed from the accommodating section 3, and returned to the lowermost portion of the section 3 again through the reading region 4, the original document thus returned is accommodated in the accommodating section 3 in the state where it is inverted from its front surface as it is fed, to the reverse surface thereof. More specifically, the one surface of the original document 2 directed upwards in FIG. 5 as said original document 2 is fed from the accommodating section 3, is inverted to be directed downwards when the original document 2 is again accommodated in the accommodating section 3 via the reading region 4.
In the case where a duplex or both side copying is to be effected through employment of the document handler RDH 1 for copying a duplex original document having information to be copied on its opposite surfaces, onto respective surfaces of a copy paper sheet corresponding to the original document, the directions indicated by the front and reverse surfaces of the original document 2 which has been read for its one surface and returned to be stacked in the accommodating section 3, are inverted as compared with those indicated by the front and reverse surfaces of said original document stored in said section 3 before the start of the copying operation. Accordingly, by way of example, in the case where, after the original document 2 is again fed from the accommodating section 3 so as to be read successively for its other surface not yet read, this original document 2 is subjected to jamming in the transport passage 6, and there is a possibility that, when the original document thus subjected to the jamming is to be returned to the accommodating section 3, the original document is again stacked, without it being noticed that the directions of the front and reverse surfaces thereof have been inverted with respect to those of said original document initially accommodated in the accommodating section 3, thus resulting in the copying of the wrong surfaces.
Moreover, in the arrangement of the known document handler RDH 1 as described so far, the original document 2 is fed from the right side at the uppermost portion of the original documents stacked in the original document accommodating section 3 in FIG. 5 at all times, and after the reading function, said original document is returned to the section 3 from the right side at the lowermost portion of the stack of the original documents. Accordingly, since the original document feeding structure to the transport passage 6 and the original document accommodating structure from the transport passage 7 are provided to be deviated towards one side (i.e. towards the right side in FIG. 5) of the original document accommodating section 3, the construction at one side of the accommodating section 3 is undesirably complicated.